1. Field of the Invention
The present invention relates to a method of and apparatus for cooling a system in which heat is generated as part of the normal operation of the system. More particularly, the present invention relates to a method of and apparatus for exhausting heat from a system into and out of which objects are not allowed to enter and exit (non-flow type of system).
2. Description of the Related Art
As is widely known, operating systems such as those of computers, communication devices, and electronic apparatus, generally have heat sources such as printed circuit boards, various interface cards and transformers. The heat sources generate heat which, if not dealt with, increases the temperature in the system. High temperatures can reduce the performance of the components of the system and even shorten the useful life of the components.
Thus, these types of systems which have heat sources are often provided with a cooling system to remove the heat generated by the heat sources.
In this respect, conventional systems are cooled by either positive pressure cooling technology or negative pressure cooling technology. The positive pressure cooling technology forcibly draws cool air into the system from the outside. On the other hand, negative pressure cooling technology establishes a negative pressure in the system by exhausting hot air from the system, whereby cool air is induced into the system from the outside.
The systems which can be cooled by the positive and the negative pressure cooling technologies need to be open systems, meaning that these systems allow some physical object, i.e., air, to be moved under pressure out of the system.
Systems employing the negative and positive pressure cooling technologies are illustrated in FIGS. 1 and 2, respectively.
Referring to FIGS. 1 and 2, a plurality of heat sources 2, 4, 6 and 8 are disposed in a housing 10b. Heat generated by the heat sources 2, 4, 6 and 8 is exhausted out of the system 10 by a cooling fan 3. More particularly, the housing 10b includes at least two ports 10a and 10a'. One of the two ports is an intake port and the other is an exhaust port. Cool air is taken into the housing 10b from the outside through the intake port. The intake cool air is mixed with hot air in the system 10 and then is forced out of the system 10 through the exhaust port.
In the system employing the positive pressure cooling technology, the cooling fan 3 is mounted in the intake port 10a' as shown in FIG. 2. In the system employing the negative pressure technology, the cooling fan 3 is mounted in the exhaust port 10a' as shown in FIG. 1.
The cooling fan 3 is connected to a control module 1. The cooling fan 3 is turned on or off by the control module 1. A temperature sensor 1a is also connected to the control module 1. The temperature in the system 10 is detected by the temperature sensor 1a and the detected temperature is inputted to the control module 1 as an electric signal.
The control module 1 receives the electric signal from the temperature sensor 1a and compares the received electric signal to a predesignated reference temperature. If the reference temperature is higher than the temperature detected by the temperature sensor 1a, the control module 1 supplies the cooling fan 3 with direct current so that negative pressure is created in the system 10 and cool air is induced into the system 10 from the outside as shown in FIG. 1, or cool air is forcibly drawn into the system 10 from the outside as shown in FIG. 2. As a result, the system is cooled.
In either case, cool air must be introduced into the system from the outside. However, fibrous materials and conductive particles may be introduced into the system together with the cool air. Such fibrous materials and conductive particles can accumulate between the wires of electric components, and semiconductor packages etc. mounted on printed circuit boards installed in the system. This in turn can increase the resistance of the wires, or short the wires, and thereby increase the temperature in the system.